Conveyor systems have long been used in various industries to move all sorts of products. To increase the usefulness and versatility of conveyors, various types of accessory equipment have been developed over the years to change the orientation of the product as it is being conveyed. One example of such an accessory is a product turner which rotates the product in its horizontal plane through any preselected angle. For example, a rectangular shaped product having two short sides and two long sides may be conveyed with either of those sides at the leading and trailing edges. For some product handling operations it is desirable to change the orientation of the product from short side leading to long side leading, or vice versa, by rotating the product in its horizontal plane through a 90.degree. angle while it is being conveyed. An example of a high speed operation which requires product in alternate orientations is palletizing or automatically stacking layers of alternately aligned product on a wooden or plastic pallet.
Various devices have been developed to turn a product on a conveyor including designs incorporating rotatable bumpers which catch a side of the product and rely on the conveyor to rotate the product about the bumper; pivotally mounted grabber bars for grabbing the product along the front and one side and pivoting the product as the conveying surface moves the opposite side of the product around; and other arrangements which work on the idea of stopping one side of the product while the conveying surface pivots the opposite side of the product.
These prior art devices suffer from a relatively slow throughput because of the relatively long time period required to complete a turn as well as the relatively large gap required between successive pieces of product to accommodate the pivoting motion of each product about a corner thereof. These prior art devices provide only a limited throughput for several reasons. Firstly, these devices pivot the product about a front corner or edge which takes a greater arcuate movement and hence more time to complete a turn than if the product were rotated about its physical center. Secondly, a larger spacing is required between successive pieces of product to provide room for the greater arcuate movement of each product. Thirdly, virtually all the prior art turners require resetting between successive pieces of product, which increases the minimum spacing permitted between product as the "work area" or "turning area" of the turner must be cleared between turns. Fourthly, virtually all of the prior art turners re-position the product at the rear of or behind the "envelope" in which the product was traveling before entering the turner. In other words, the turner slows down the product during the turn and fails to turn it on its physical center at the conveyor surface speed. This further increases the gap required between product and reduces the throughput. As a result of these and other factors, the surface speed of the conveyor and of individual pieces of product thereon might be quite substantial, while the throughput and delivery of the system is significantly reduced because of the wasted space between successive pieces of product.
Some prior art systems have sought to improve the throughput of turners by utilizing sections of speed up conveyor before the turner which increases the spacing between product, but also increases its speed. Thus, the product is subjected to significantly rougher handling at a higher speed, while the rest of the system is limited to a lower speed and throughput. Furthermore, the mechanical limits of the turner are reached much more rapidly and the rest of the system is locked into a lower speed and throughput.
Because of the low throughput of the prior art product turners, many other automatic machines which depend upon a conveyor input of product through a product turner must also operate at speeds much slower than their rated capacity, thereby limiting their usefulness and throughput. One example of such an arrangement is the automatic palletizing machines which stack product on pallets by layers, with each layer having a different product orientation to achieve a balanced and stable pallet. In these applications, generally a single conveyor brings product to the input side of the palletizing machine in one orientation with every other row or layer of product being turned by a product turner to achieve the proper orientation. Although some of the machines presently available have performance design characteristics which approach the fastest delivery capabilities of present day high speed conveyor designs, prior art product turners can generally operate at only 50% of these top conveyor throughputs and thereby severely limit the speed at which the automatic palletizer may form properly stacked pallets. Thus, the ineffectiveness of a relatively minor component such as a product turner may affect the advisability of investing in much larger and faster equipment which would otherwise significantly improve the throughput and profitability of an automatic operation.
To solve these and other problems in the prior art product turners, applicant has succeeded in designing and developing a new product turner which turns product near its physical center, resets during the turning motion, and accelerates the product through the turn which permits it to operate at a much higher rate approaching and even matching in some instances the product throughout capabilities of present day high velocity conveyors.
Furthermore, applicant's turner actually turns the product within the forward portion of its original envelope, so that it actually increases the gap available in the "working area" when product is being turned from short side leading to long side leading. These advantages combined with the short stroke of the turner drastically reduce the required gap between product which significantly increases its throughput for any conveyor or speed over prior art turners.
Applicant's design can be readily incorporated into a conveyor module for convenient insertion into an existing conveyor stream. Alternately, applicant's product turner may be added by the simple removal and replacement of two driven rollers in a power roller conveyor, the addition of several guide bumpers and a guide bracket, and a photoelectric relay.
Applicant's product turner generally includes an over-sized roller at the entry section to accelerate the product into the turner and agitate the product and make it easier for it to be lifted. This input roller may be tapered and mounted with one end slightly above the conveying surface, or have a single beveled knurl at one end to ensure that the product is skewed slightly into its turn. This prevents any product from entering the turner skewed in the wrong direction which might happen should it have an uneven or damaged bottom or be otherwise mis-aligned. The actual turning of the product is accomplished by a powered roller having a knurl with several different beveled surfaces for pushing, lifting and accelerating, and "whipping" the product as a powered cylinder deflects and returns the knurl and roller transversely underneath the product.
The turning action is started by a light source and sensor which senses the leading edge of the product and as it reaches the roller and knurl, the powered cylinder is operated to bring the knurl into contact with the side thereof. A first beveled surface is formed at a relatively steep angle to "catch" the side of the product and push or skew it quickly. As the knurl pushes against the forward portion of one side, a guide bumper remains in contact with the rearward portion of the opposite side to start the product rotating about its center. The knurl continues its deflection until the forward portion of the opposite side contacts a second guide bumper such that the opposite side is riding against two guide bumpers. If the knurl has not already begun to lift the case, it then does so by sliding under the rear corner of the product over a second and third bevel of the knurl. As this is happening, the forward speed of the conveyor brings the front side of the product into contact with a third somewhat larger guide bumper. By this time the flattened portion of the knurl arrives underneath the rear corner of the product to smoothly accelerate that corner, and the knurl is simultaneously retracted to "whip" the rear of the product around the third guide bumper. This returning transverse movement, combined with the accelerating force of the flattened bevel, effectively whips the rear edge of the product around and completes the turn. It should be understood that the product may actually rest on a narrow portion of one or more of the bevels, or even the line of transition between them. The front edge of the product remains substantially in contact with the guide bumper which "walks around" as the product is turned. A guide bracket along the edge of the conveyor helps catch the side of the product as it is whipped around and aligns it as it moves out of the turner.
As can be appreciated, applicant's product turner has significant advantages over the prior art. As can be better visualized from the drawings, the product is turned by being rotated virtually about its physical center, which reduces the turning time and the gap required between successive pieces of product. Additionally, unlike virtually every prior art product turner, a rotating, reciprocating knurl is used to first offset the case from its original path and then whip the rear edge of the product around and thereby push it into a forward portion of its original envelope (or at least its center) which actually increases the gap available in the working area for the next product. The relatively short stroke of the fast acting drive cylinder provides a very quick cycle time and the cylinder is reset as it completes a cycle. Additionally, by "pushing" the product through a good portion of the desired angular movement, the dead time of the prior art in waiting for the momentum of the case itself to produce the angular rotation is eliminated. Most prior art product turners stop a corner or edge of the product and wait for the opposite side to build up momentum, thereby creating a turning moment which achieves the turn. As can be appreciated, this takes time and reduces the throughput. Thus, applicant has developed a product turner having an elegantly simple design and utilizing a fast acting, direct action traveling roller and knurl which drastically reduces the gap required between successive pieces of product, pushes the product through a good portion of the desired angular movement, resets itself as part of its relatively short cycle, and thereby significantly increases the throughput capability of any conveyor system with which it is used.
Other advantages and features of applicant's product turner may be more fully understood by referring to the drawings and description of the preferred embodiment which follows.